An investigation will be made of the properties and regulation of glycogen synthase in rabbit muscle and liver in vitro and in vivo. Synthase kinases will be purified and characterized from muscle and liver. Regulation of kinases by calcium, calmodulin, and cyclic nucleotides will be examined. Relationships between phosphorylation, activity, and structure of synthase will be studied. Binding of glucose-6-P and UDP-glucose to muscle synthase will be determined. Phosphorylation of synthase in vivo will be studied in response to epinephrine, insulin, and diabetes. Effects of somatostatin infusion will be examined. The in vivo phosphorylation state of each of the sites in muscle synthase will be determined by analysis of tryptic peptides separated by high performance liquid chromatography.